1. Technical Field
The present invention relates to an ink jet recording ink composition, and more particularly, to an ink jet recording ink composition superior in rub fastness, dry cleaning resistance, and ejection stability.
2. Related Art
Pigments are often used as coloring agents for ink jet recording ink because of their superior fastness to, for example, water and light. Typically, pigments have low solubilities. In order to enhance the dispersion stability of a pigment in an ink, a dispersant, such as a surfactant or a polymer, is added to the ink. Resins having both a hydrophilic portion and a hydrophobic portion, such as styrene-acrylic copolymers, are generally used as the dispersant.
For ink jet recording, high printing properties are required of ink jet recording ink. For example, it is required not to cause bleeding, to dry rapidly, to be printed uniformly on various types of recording medium, and not to cause color mixing between adjacent printed images. In order to enhance these printing properties, in general, various additives are added to the ink. For example, in order to enhance the penetration in recording media and thus to reduce the bleeding, a glycol ether, such as diethylene glycol monobutyl ether, may be added (U.S. Pat. No. 5,156,675), or an acetylene glycol surfactant may be added (U.S. Pat. No. 5,183,502). In U.S. Pat. No. 5,196,056, both of them are added.
However, if a surfactant or a glycol ether is present in an ink containing a pigment dispersant, the pigment is liable to adsorb or separate the dispersant resin, thereby degrading the storage stability of the ink. In addition, if the dispersant separated from the pigment remains in the ink, the viscosity of the ink may be increased to degrade the ink ejection stability.
JP-T-2007-522285 discloses an ink jet ink composition containing a crosslinked polyurethane dispersion and exhibiting improved washing fastness on a textile printed by an ink jet method therewith. On the other hand, an ink jet ink composition exhibiting high stability and fixability has been being desired, particularly for textile use.